Multi-mode communication terminal

ABSTRACT

The present invention aims to provide a multimode communication terminal capable of controlling a charging operation in accordance with a communication schema during communication for each of plural communication schemas.  
     The terminal includes a first communication unit  10  for communicating based on the first communication schema, a second communication unit  11  for communicating based on the second communication schema, a communication schema switching unit  12  for selecting one of the first communication unit  10  and the second communication unit  11  thereby to switch the communication schema, a control unit  13  for managing the selection states of the communication schema switching unit  12  and a charging control method switching unit  14,  a first charging control unit  15  for controlling the charging operation of a secondary battery  17  when the first communication unit  10  is selected, a second charging control unit  16  for controlling the charging operation of the secondary battery  17  when the first communication unit  10  is selected, the charging control method switching unit  14  selecting one of the first charging control unit  15  and the second charging control unit  16  thereby to switch the charging control method, and the secondary battery  17  whose charging operation is controlled by the first charging control unit  15  or the second charging control unit  16.

TECHNICAL FIELD

The present invention relates to a multimode communication terminalcapable of controlling a charging operation in accordance with acommunication schema during communication for each of a plurality ofcommunication schemas.

BACKGROUND ART

A secondary battery has been mainly used as the power source of a mobilecommunication terminal. As disclosed in JP-A-5-111184, for example, thecharging operation of a secondary battery has been controlled in such amanner that constant current control is performed so as to make acharging current constant until the battery voltage of the secondarybattery reaches a predetermined value, then constant voltage control isperformed so as to make the battery voltage constant after the batteryvoltage reaches the predetermined value, then the charging current ismonitored during the constant voltage control and the charging operationis terminated when the charging current reduces to a predetermined valueor less.

In a mobile communication terminal for the TDMA communication schemasuch as GSM or PDC, a time-division radio signal is transmitted andreceived. In such a terminal, since a large electric power is requiredat the time of transmission, a consumption power of the terminaltemporally changes extremely during the communication. As a result, itis difficult to measure a charging current supplied to a secondarybattery and the battery voltage of the secondary battery. Thus, duringthe communication, even when the battery voltage of the secondarybattery reaches a predetermined value, the aforesaid constant voltagecontrol is not carried out. That is, instead of carrying out theconstant voltage control, the charging control is performed in a mannerthat the charging operation is temporarily stopped and restarted afterthe termination of the communication or that a charging current iscontrolled so as not to be an overcurrent but to be a predeterminedvalue or less by setting the charging voltage to a low value.

In the mobile communication terminal for the W-CDMA communicationschema, since the temporal changing degree of a consumption power duringthe communication is small as compared with the TDMA communicationschema, it is easy to measure a charging current supplied to a secondarybattery and the battery voltage of the secondary battery. Thus, in thecase of the W-CDMA communication schema, the aforesaid constant voltagecontrol can be carried out even during the communication.

(Patent Document 1)

-   -   JP-A-5-111184

In this manner, since the temporal changing degree of a consumptionpower during the communication differs depending on the communicationschema, it is preferable to suitably perform the charging control of asecondary battery depending on the communication schema. However, theconventional charging control was not differentiated depending on thecommunication schema. Thus, when communication is performed during thecharging operation of a secondary battery in a multimode communicationterminal conformed to both the TDMA communication schema and the W-CDMAcommunication schema, for example, a charging current and a batteryvoltage can be measured accurately when the communication is performedbased on the W-CDMA communication schema but can not be measuredaccurately when the communication is performed based on the TDMAcommunication schema.

In the conventional charging control operation, when a charging currentcan not be measured accurately in a manner that the charging current ismeasured as a value smaller than an actual current value, the chargingoperation is terminated even when the battery is not fully charged. Incontrast, in the case where the charging current is measured as a valuelarger than an actual current value, the charging operation is continuedeven when it becomes a state to terminate the charging operation.Particularly, in the latter case, there arises a problem that anovervoltage is applied to the secondary battery. Further, in theconventional charging control operation, when a battery voltage can notbe measured accurately in a manner that the charging voltage is measuredas a value smaller than an actual voltage value, an overvoltage may beapplied to the secondary battery during the charging operation.

In order to avoid such problems, the charging operation may betemporarily stopped when the communication schema is switched during thecharging operation. However, in this case, although the chargingoperation can be performed normally during the communication operationbased on the W-CDMA communication schema, since the charging operationis temporarily stopped, there arises a problem that it takes a long timeto complete the charging operation.

The invention is made in view of the aforesaid problems of theconventional technique and an object of the invention is to provide amultimode communication terminal which can control a charging operationin accordance with a communication schema during communication for eachof a plurality of communication schemas.

DISCLOSURE OF THE INVENTION

In order to attain the aforesaid object, the multimode communicationterminal according to the invention is arranged in a manner that in themultimode communication terminal which includes a secondary battery andcontrols a charging operation of the secondary battery in accordancewith a communication schema during communication, the multimodecommunication terminal includes: communication means capable ofcommunicating in accordance with a plurality of communication schemas;communication schema switching means for controlling the communicationmeans in a manner that a communication schema is switched into adesignated communication schema among the plurality of communicationschemas thereby to communicate in accordance with the designatedcommunication schema; charging control means for controlling a chargingoperation of the secondary battery by a different charging controlmethod in accordance with each of the plurality of communicationschemas; and charging control method selecting means for selecting thecharging control method for charging the secondary battery by thecharging control means in accordance with the communication schema ofcommunication being performed by the communication means. Accordingly,the charging operation can be controlled in accordance with thecommunication schema during communication so as to conform to each of aplurality of the communication schemas.

Further, the multimode communication terminal according to the inventionfurther includes: battery voltage detection means for detecting abattery voltage of the secondary battery; and charging current detectionmeans for detecting a charging current supplied to the secondarybattery, wherein the communication means is conformed to a CDMAcommunication schema and a TDMA communication schema, the chargingcontrol means performs constant-current and constant voltage chargingcontrol when the communication means communicates based on the CDMAcommunication schema, and the charging control means, while thecommunication means communicates based on the TDMA communication schema,performs constant-current charging control when a battery voltage of thesecondary battery detected by the battery voltage detection means isless than a predetermined voltage threshold value, and stops chargingoperation when a battery voltage of the secondary battery detected bythe battery voltage detection means is equal to or larger than thepredetermined voltage threshold value. Thus, during the communicationbased on the CDMA communication schema, the charging operation can becompleted quickly without stopping the charging operation. As a result,the charging operation can be performed efficiently. On the other hand,during the communication based on the TDMA communication schema, such aphenomenon can be prevented from occurring that the completion of thecharging operation is erroneously detected thereby to terminate thecharging operation despite of a non-full-charge state or to apply anovervoltage to the secondary battery.

Furthermore, the multimode communication terminal according to theinvention further includes detection timing generation means forgenerating, in accordance with the communication schema, a timing fordetecting a charging current supplied to the secondary battery by thecharging current detection means and a timing for detecting a batteryvoltage of the secondary battery by the battery voltage detection means,wherein the detection timing generation means generates timings of apredetermined period when the communication means communicates based onthe CDMA communication schema, and generates timings avoiding a signaltransmission timing of the communication means when the communicationmeans communicates based on the TDMA communication schema. Thus, theoptimum detection timings can be set at both the cases where thecommunication is performed based on the CDMA communication schema andwhere the communication is performed based on the TDMA communicationschema. In particular, since the detection timings are set so as toavoid the signal transmission timings when the communication isperformed based on the TDMA communication schema, the charging controlcan be performed based on the charging current values and the batteryvoltage values detected at suitable timings for any of the communicationschemas.

Furthermore, the multimode communication terminal according to theinvention is arranged in a manner that the charging control meansswitches the charging control method in accordance with switching of thecommunication schema for communication performed by the communicationmeans. Thus, even when the communication schema is switched during thecharging operation, the charging operation can be controlled so as toconform to the communication schema after the switching.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of the multimodecommunication terminal according to the first embodiment;

FIG. 2 is a flowchart for explaining the operation of the multimodecommunication terminal according to the first embodiment;

FIG. 3 is a block diagram showing the configuration of the multimodecommunication terminal according to the second embodiment;

FIG. 4 is an explanatory diagram showing charging curves of a secondarybattery which is subjected to constant-current and constant voltagecharging control;

FIG. 5 is a block diagram showing the configuration of the multimodecommunication terminal according to the third embodiment; and

FIG. 6 is a timing chart showing the charging current detection timingsand the GSM radio signal transmission timings at the multimodecommunication terminal of the third embodiment.

In the drawings, a reference numeral 10 refers to a first communicationunit, 11 to a second communication unit, 12 and 22 to communicationschema switching units, 13, 23 and 33 to control units, 14 to a chargingcontrol method switching unit, 15 to a first charging control unit, 16to a second charging control unit, 17 and 26 to secondary batteries, 18and 27 to external power sources, 20 to a W-CDMA communication unit, 21to a GSM communication unit, 24 to a charging control unit, 25 and 31 tobattery voltage detection units, 30 to a detection timing generationunit, and 32 and 28 to charging current detection units.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a multimode communication terminal accordingto the invention will be explained in detail with reference to thedrawings in the order of (a first embodiment), (a second embodiment) and(a third embodiment).

(First Embodiment)

FIG. 1 is a block diagram showing the configuration of the multimodecommunication terminal according to the first embodiment. As shown inthis figure, the multimode communication terminal 1 of the firstembodiment is configured to include a first communication unit 10 and asecond communication unit 11 corresponding to a communication means ofclaims, a communication schema switching unit 12 corresponding to acommunication schema switching means, a control unit 13, a chargingcontrol method switching unit 14 corresponding to a charging controlmethod selecting means, a first charging control unit 15 and a secondcharging control unit 16 corresponding to a charging control means, anda secondary battery 17 The multimode communication terminal 1 is capableof being coupled to an external power source 18 through an AC adapter sothat the external power source 18 can charge the secondary battery 17through the first charging control unit 15 or the second chargingcontrol unit 16.

Hereinafter, the explanation will be made as to the respectiveconstituent elements of the multimode communication terminal 1 accordingto the embodiment.

The first communication unit 10 communicates with a base station etc.based on the first communication schema. The second communication unit11 communicates with a base station etc. based on the secondcommunication schema. The communication schema switching unit 12 selectsone of the first communication unit 10 and the second communication unit11 thereby to switch the communication schema. The control unit 13entirely controls the multimode communication terminal 1 and manages theselecting states of the communication schema switching unit 12 and thecharging control method switching unit 14.

The first charging control unit 15 controls the charging operation ofthe secondary battery 17 when the first communication unit 10 (firstcommunication schema) is selected by the communication schema switchingunit 12. The second charging control unit 16 controls the chargingoperation of the secondary battery 17 when the second communication unit11 (second communication schema) is selected by the communication schemaswitching unit 12. The charging control method switching unit 14 selectsone of the first charging control unit 15 and the second chargingcontrol unit 16 thereby to switch the charging control method. Thesecondary battery 17 is a power source for the multimode communicationterminal 1 and the charging operation of the secondary battery iscontrolled by the first charging control unit 15 or the second chargingcontrol unit 16.

Next, the operation of the multimode communication terminal 1 accordingto the embodiment will be explained with reference to FIG. 2. FIG. 2 isa flowchart for explaining the operation of the multimode communicationterminal 1 according to the first embodiment. In particular, thisflowchart explains the charging control method by the control unit 13 atthe time of starting the charging operation of the secondary battery 17while the multimode communication terminal 1 communicates based on thefirst or second communication schema or at the time of startingcommunication during the charging operation.

As shown in FIG. 2, the control unit 13 determines as to which one ofthe first communication unit 10 and the second communication unit 11 isselected by the communication schema switching unit 12 (step S201). Whenit is determined that the first communication unit 10 is selected instep S201, the process proceeds to step S203, whilst when it isdetermined that the second communication unit 11 is selected, theprocess proceeds to step S205. In step S203, the control unit 13instructs the charging control method switching unit 14 to select thefirst charging control unit 15. In contrast, in step S205, the controlunit 13 instructs the charging control method switching unit 14 toselect the second charging control unit 16. After steps S203 and S205,the control unit 13 determines whether or not the communication schemais switched due to hand-over etc. When it is determined that thecommunication schema is switched, the process returns to step S201.

As explained above, the multimode communication terminal 1 according tothis embodiment can control the charging operation in accordance withthe communication schema during communication so as to conform to eachof a plurality of the communication schemas. Further, even when thecommunication schema is switched during the charging operation, thecharging operation can be controlled so as to conform to thecommunication schema after the switching.

(Second Embodiment)

FIG. 3 is a block diagram showing the configuration of the multimodecommunication terminal according to the second embodiment. As shown inthis figure, a multimode communication terminal 2 of the secondembodiment is configured to include a W-CDMA communication unit 20 and aGSM communication unit 21 corresponding to a communication means ofclaims, a communication schema switching unit 12 corresponding to acommunication schema switching means, a control unit 23, a chargingcontrol unit 24 corresponding to a charging control means and a chargingcontrol method selecting means, a battery voltage detection unit 25corresponding to a battery voltage detection means, a charging currentdetection unit 28 corresponding to a charging current detection means,and a secondary battery 26. The multimode communication terminal 2 iscapable of being coupled to an external power source 27 through an ACadapter so that the external power source 27 can charge the secondarybattery 26 through the charging control unit 24.

Hereinafter, the explanation will be made as to the respectiveconstituent elements of the multimode communication terminal 2 accordingto the embodiment.

The W-CDMA communication unit 20 communicates with a base station etc.based on the CDMA communication schema. The GSM communication unit 21communicates with a base station etc. based on the TDMA communicationschema. The communication schema switching unit 22 switches thecommunication schema by selecting one of the W-CDMA communication unit20 and the GSM communication unit 21. The control unit 23 entirelycontrols the multimode communication terminal 2, manages the selectingstates of the communication schema switching unit 22 and instructs thecharging control unit 24.

The charging control unit 24 suitably controls the charging operation inaccordance with the selected communication unit (the W-CDMAcommunication unit 20 or the GSM communication unit 21). In thisembodiment, the charging control unit 24 performs constant-current andconstant-voltage charging control at the time of charging the secondarybattery 26 from the external power source 27 when the W-CDMAcommunication unit 20 is selected. In the constant-current andconstant-voltage charging control, a constant-current charging controland a constant voltage charging control are selectively performed inaccordance with a charging state in a manner that, as shown in FIG. 4the constant-current charging control for controlling a charging currentto a constant value (for example, 700 mA) is performed until a batteryvoltage reaches a predetermined threshold voltage value (for example,4.1 V) after starting the charging operation, whilst the constantvoltage charging control for controlling the battery voltage to aconstant value (the predetermined threshold voltage value) until thecharging current reduces to a predetermined threshold current value (forexample, 70 mA) after the battery voltage reaches the predeterminedthreshold voltage value.

In contrast, the charging control unit 24 controls the chargingoperation of the secondary battery 26 when the GSM communication unit 21is selected in a manner that the constant-current charging control isperformed when the battery voltage of the secondary battery 26 detectedby the battery voltage detection unit 25 is the battery voltage (lessthan the predetermined threshold voltage value) at the time ofperforming the aforesaid constant-current charging control, whilst thecharging operation is temporarily stopped when the detected batteryvoltage is equal to or more than the battery voltage (the predeterminedthreshold voltage value) at the time of performing the aforesaidconstant-voltage charging control.

The battery voltage detection unit 25 detects the battery voltage of thesecondary battery 26. The battery voltage value detected by the batteryvoltage detection unit 25 is utilized in order to determine theswitching from the constant-current charging to the constant-voltagecharging, to perform the constant-voltage charging control by thecharging control unit 24 and to stop the charging when the batteryvoltage becomes an abnormally high or low value. The charging currentdetection unit 28 detects the charging current supplied to the secondarybattery 26. The charging current value detected by the charging currentdetection unit 28 is utilized in order to perform the constant-currentcharging control by the charging control unit 24, to complete thecharging operation when the charging current reduces to a thresholdvalue or less at the time of the constant voltage charging, and to stopthe charging when the battery current becomes an abnormally large value.

The secondary battery 26 is a power source for the multimodecommunication terminal 2 and the predetermined charging control for thebattery is performed by the charging control unit 24 in the aforesaidmanner during the charging.

In this embodiment, like the first embodiment, when the communicationschema is switched due to the hand-over etc. during the charging, thecontrol unit 23 of the multimode communication terminal 2 switches theinstruction to the charging control unit 24 depending on which one ofthe W-CDMA communication unit 20 and the GSM communication unit 21 isselected.

As explained above, the multimode communication terminal 2 of thisembodiment provided with the aforesaid constituent elements performs theconstant-current and constant-voltage charging control for the chargingduring the communication by the W-CDMA communication schema, whilstperforms the constant-current charging control by the battery voltage ofthe secondary battery 26 or the charging operation stop control for thecharging during the communication by the GSM communication schema.Further, even when the communication schema is switched during thecommunication, the charging control conformed to the communicationschema after the switching is performed. Thus, during the communicationbased on the W-CDMA communication schema, the charging operation can becompleted quickly without stopping the charging operation. On the otherhand, during the communication based on the GSM communication schema,such a phenomenon can be prevented from occurring that the completion ofthe charging operation is erroneously detected thereby to terminate thecharging operation despite of a non-full-charge state or to apply anovervoltage to the secondary battery 26.

Further, since the charging control unit 24 can be commonly used at thetime of communicating based on the GSM communication schema as well asat the time of communicating based on the W-CDMA communication schema, acircuit for realizing the charging control unit 24 can be made smalleras compared with a circuit including the first charging control unit 15and the second charging control unit 16 of the first embodiment.

(Third Embodiment)

FIG. 5 is a block diagram showing the configuration of the multimodecommunication terminal according to the third embodiment. In thisfigure, portions identical to those of FIG. 3 (the second embodiment),that is, the W-CDMA communication unit 20, the GSM communication unit21, the communication schema switching unit 22, the charging controlunit 24 and the secondary battery 26 are referred to by the commonsymbols, with explanation thereof being omitted. In addition to theseconstituent elements, the multimode communication terminal 3 accordingto the third embodiment further includes a control unit 33, a detectiontiming generation unit 30 corresponding to a detection timing generatingmeans, a battery voltage detection unit 31 corresponding to a batteryvoltage detection means, and a charging current detection unit 32corresponding to a charging current detection means.

The control unit 33 entirely controls the multimode communicationterminal 3, manages the selecting operation of the communication schemaswitching unit 12, instructs the charging control unit 24 and instructstimings to the detection timing generation unit 30 in accordance withthe communication schema during the communication. The timinginstruction to the detection timing generation unit 30 means to instructthe detection timing generation unit 30 so as to generate detectiontimings of the charging current or the battery voltage at predeterminedtimings when the W-CDMA communication unit 20 is selected, and toinstruct the detection timing generation unit 30 to generate detectiontimings avoiding the signal transmission timings when the GSMcommunication unit 21 is selected. The predetermined timings may be anarbitrary period or the frame period of the W-CDMA communication schema.

The detection timing generation unit 30 generates timings for detectingthe battery voltage of the secondary battery 26 and the charging currentsupplied to the secondary battery 26 at timings avoiding the GSMtransmission timings based on the timings instructed from the controlunit 33, timings of the predetermined period or the GSM system timingsfrom the GSM communication unit 21. Thus, as shown in FIG. 6, each ofthe charging current detection unit 32 and the battery voltage detectionunit 31 performs the detection at the timings avoiding sections (thatis, the radio wave transmission timings) where the GSM communicationunit 21 transmits signals. FIG. 6 is a timing chart showing the chargingcurrent detection timings and the GSM radio signal transmission timingsat the multimode communication terminal 3 of the third embodiment.

The battery voltage detection unit 31 detects the battery voltage of thesecondary battery 26 at the timings generated by the detection timinggeneration unit 30. The charging current detection unit 32 detects thecharging current supplied to the secondary battery 26 at the timingsgenerated by the detection timing generation unit 30. The batteryvoltage value detected by the battery voltage detection unit 31 and thecharging current value detected by the charging current detection unit32 are used for the constant-current and constant-voltage chargingcontrol performed by the charging control unit 24.

In this embodiment, like the first or second embodiment, when thecommunication schema is switched due to the hand-over etc. during thecharging, the control unit 33 of the multimode communication terminal 3switches the instruction to the detection timing generation unit 30depending on which one of the W-CDMA communication unit 20 and the GSMcommunication unit 21 is selected.

As explained above, the multimode communication terminal 3 of thisembodiment provided with the aforesaid constituent elements sets mostsuitably the detection timings of the charging current or the batteryvoltage at each cases where the W-CDMA communication unit 20 is selectedand the GSM communication unit 21 is selected. In particular, since thedetection timings are set so as to avoid the signal transmission timingswhen the GSM communication unit 21 is selected, the constant-current andconstant-voltage charging control can be performed based on the chargingcurrent values and the battery voltage values detected at suitabletimings for any of the communication schemas.

Although, in the first to third embodiments explained above, theexplanation is made as to the multimode communication terminal conformedto the two kinds of communication schemas, the similar effects can beattained for a multimode communication terminal conformed to three ormore kinds of communication schemas. Further, the communication schemasare not limited to the W-CDMA communication schema and the GSMcommunication schema, but the PDC communication schema, the PHScommunication schema or the analog signal communication schema may beapplied to the invention. In this case, the charging control isperformed so as to conform to the charging characteristics of each ofthe communication schemas.

It should be clear for those skilled in the art that although theinvention has been explained in detail with reference to the particularembodiments, the invention is not limited thereto and various changesand modifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

The present application is based on Japanese Patent Application No.2002-266919 filed on Sep. 12, 2002, the contents of which isincorporated herein by reference.

Industrial Applicability

As explained above, according to the multimode communication terminal ofthe invention, the charging operation can be controlled in accordancewith the communication schema during the communication so as to conformwith each of a plurality of the communication schemas.

1. A multimode communication terminal having a secondary batterycontrolling a charging operation of the secondary battery in accordancewith a communication schema during communication, said multimodecommunication terminal comprising: communication means capable ofcommunicating in accordance with a plurality of communication schemas;communication schema switching means for controlling the communicationmeans in a manner that a communication schema is switched into adesignated communication schema among the plurality of communicationschemas thereby to communicate in accordance with the designatedcommunication schema; charging control means for controlling a chargingoperation of the secondary battery by a different charging controlmethod in accordance with each of the plurality of communicationschemas; and charging control method selecting means for selecting thecharging control method for charging the secondary battery by thecharging control means in accordance with the communication schema ofcommunication being performed by the communication means.
 2. Themultimode communication terminal according to claim 1, furthercomprising: battery voltage detection means for detecting a batteryvoltage of the secondary battery; and charging current detection meansfor detecting a charging current supplied to the secondary battery,wherein the communication means is conformed to a CDMA communicationschema and a TDMA communication schema, wherein the charging controlmeans performs constant-current and constant voltage charging controlwhen the communication means communicates based on the CDMAcommunication schema, and wherein, while the communication meanscommunicates based on the TDMA communication schema, the chargingcontrol means performs constant-current charging control when a batteryvoltage of the secondary battery detected by the battery voltagedetection means is less than a predetermined voltage threshold value,and stops charging operation when a battery voltage of the secondarybattery detected by the battery voltage detection means is equal to orlarger than the predetermined voltage threshold value.
 3. The multimodecommunication terminal according to claim 2, further comprising:detection timing generation means for generating, in accordance with thecommunication schema, a timing for detecting a charging current suppliedto the secondary battery by the charging current detection means and atiming for detecting a battery voltage of the secondary battery by thebattery voltage detection means, wherein the detection timing generationmeans generates timings of a predetermined period when the communicationmeans communicates based on the CDMA communication schema, and generatestimings avoiding a signal transmission timing of the communication meanswhen the communication means communicates based on the TDMAcommunication schema.
 4. The multimode communication terminal accordingto claim 1, 2 or 3, wherein the charging control means switches thecharging control method in accordance with switching of thecommunication schema for communication performed by the communicationmeans.